Re: [PATCH] drm/imagination: fix ARRAY_SIZE build error

From: Matt Coster
Date: Thu Jan 18 2024 - 05:04:19 EST

On 10/01/2024 00:23, Randy Dunlap wrote:
Fix a build error when using GCC 13.2.0 from kernel.org crosstools
by changing ARRAY_SIZE() to the macro PVR_MIPS_PT_PAGE_COUNT:

I assume you're referring to the x86_64 => aarch64 toolchain here?

drivers/gpu/drm/imagination/pvr_vm_mips.c: In function 'pvr_vm_mips_fini':
../include/linux/array_size.h:11:25: warning: overflow in conversion from 'long unsigned int' to 'int' changes value from '18446744073709551615' to '-1' [-Woverflow]
11 | #define ARRAY_SIZE(arr) (sizeof(arr) / sizeof((arr)[0]) + __must_be_array(arr))
| ^
drivers/gpu/drm/imagination/pvr_vm_mips.c:105:24: note: in expansion of macro 'ARRAY_SIZE'
105 | for (page_nr = ARRAY_SIZE(mips_data->pt_pages) - 1; page_nr >= 0; page_nr--) {
| ^~~~~~~~~~

I can't seem to reproduce this using the above toolchain (or any other),
even with -Woverflow explicitly specified.

The use of ARRAY_SIZE() in loop bounds is a pretty common construction –
even within the pvr driver. Do you see similar warnings anywhere else?

Regards,
Matt

--
Matt Coster
Imagination Technologies

Fixes: 927f3e0253c1 ("drm/imagination: Implement MIPS firmware processor and MMU support")
Signed-off-by: Randy Dunlap <rdunlap@xxxxxxxxxxxxx>
Cc: Donald Robson <donald.robson@xxxxxxxxxx>
Cc: Maxime Ripard <mripard@xxxxxxxxxx>
Cc: Frank Binns <frank.binns@xxxxxxxxxx>
Cc: Matt Coster <matt.coster@xxxxxxxxxx>
Cc: Maarten Lankhorst <maarten.lankhorst@xxxxxxxxxxxxxxx>
Cc: Thomas Zimmermann <tzimmermann@xxxxxxx>
Cc: David Airlie <airlied@xxxxxxxxx>
Cc: Daniel Vetter <daniel@xxxxxxxx>
Cc: dri-devel@xxxxxxxxxxxxxxxxxxxxx
---
drivers/gpu/drm/imagination/pvr_vm_mips.c | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)

diff -- a/drivers/gpu/drm/imagination/pvr_vm_mips.c b/drivers/gpu/drm/imagination/pvr_vm_mips.c
--- a/drivers/gpu/drm/imagination/pvr_vm_mips.c
+++ b/drivers/gpu/drm/imagination/pvr_vm_mips.c
@@ -46,7 +46,7 @@ pvr_vm_mips_init(struct pvr_device *pvr_
if (!mips_data)
return -ENOMEM;
- for (page_nr = 0; page_nr < ARRAY_SIZE(mips_data->pt_pages); page_nr++) {
+ for (page_nr = 0; page_nr < PVR_MIPS_PT_PAGE_COUNT; page_nr++) {
mips_data->pt_pages[page_nr] = alloc_page(GFP_KERNEL | __GFP_ZERO);
if (!mips_data->pt_pages[page_nr]) {
err = -ENOMEM;
@@ -102,7 +102,7 @@ pvr_vm_mips_fini(struct pvr_device *pvr_
int page_nr;
vunmap(mips_data->pt);
- for (page_nr = ARRAY_SIZE(mips_data->pt_pages) - 1; page_nr >= 0; page_nr--) {
+ for (page_nr = PVR_MIPS_PT_PAGE_COUNT - 1; page_nr >= 0; page_nr--) {
dma_unmap_page(from_pvr_device(pvr_dev)->dev,
mips_data->pt_dma_addr[page_nr], PAGE_SIZE, DMA_TO_DEVICE);

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